Modeling and Analysis of Mono Composite Leaf Spring under ... · The leaf spring have more advantage over helical spring since the ends of the spring may be guided along a definite

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438

Volume 4 Issue 6, June 2015

www.ijsr.net Licensed Under Creative Commons Attribution CC BY

Modeling and Analysis of Mono Composite Leaf

Spring under the Dynamic load condition using

FEA for LCV

Adapa. Mahanth Kumar1, B. Sreenivasa Kumar Reddy

2

1, 2 JNTU College of Engineering Pulivendula, Dept. of Mechanical Engineering, Pulivendula - 516390, Kadapa, Andhra Pradesh, India.

Abstract: Leaf springs are widely used as automotive suspension to absorb shock loads. Suspension system in an automobile

determines the riding comfort of passengers and the amount of damage to the vehicle. The main function of leaf spring assembly as

suspension element is not only to support vertical load, but also to isolate road-induced vibrations. Another part has to be concentrated,

is the automobile industry has shown increased interest in the replacement of steel spring with composite leaf spring due to strength

factor and stiffness. Since the composite materials have more elastic strain energy storage capacity and high strength-to-weight ratio as

compared to those of steel. It is possible to reduce the weight of the leaf spring without any reduction on load carrying capacity and

stiffness. Therefore, analysis of the composite material becomes equally important to study the behavior of Composite Leaf Spring. The

objective of the project is to replace the multi-leaf steel spring by mono composite leaf spring for the same load carrying capacity and

stiffness by compare stresses and frequencies. Mono-composite leaf spring is designed for the same design specification except

thickness so as to obtain the same stiffness for the same load carrying capacity and boundary conditions. Three different composite

materials have been considered. They are e-glass/epoxy, graphite/epoxy and carbon/epoxy. Modeling is done by using CATIA V5 R19

and analysis is carried out by using ANSYS 15.0 software.

Keywords: Leaf Spring, Composite materials, ANSYS V 15, CATIA V5 R19.

1. Introduction

Ever increasing needs of high performance together with

increased life and light weight leads to consistent

development of nearly each part of automobile. In

Automobile Industry present day’s Composite materials are

used in place of metal parts. The performance characteristics

of automobile are not only depend on shape and geometry

but also stiffness is an important factor. Weight reduction of

material used in automobile is mainly focused by automobile

manufacturer for conserving natural resources and

economizes energy. Better manufacturing processes. Design

optimization and better material will leads to Weight

reduction.

It is noted that absorb and release of store energy is done by

springs which are the suspension elements. Hence, the strain

energy of the material used becomes a major factor in

designing the springs. The relationship between the specific

strain energy and stress can be

U= σ 2 / ρ E

Where σ is the strength, ρ the density and E the Young’s

modulus of the spring material. It can be clearly noted that

material having greater specific strain energy capacity will

have lower modulus and lower density.

The leaf spring plays a vital role in automobile application

which is one of the important components to provide a good

suspension to absorb shocks. It carries lateral loads, brake

and driving torque in addition to shock absorbing. The leaf

spring have more advantage over helical spring since the

ends of the spring may be guided along a definite path as it

deflects to act as a structural member in addition to energy

absorbing device.

10℅ to 20℅ of the unsprang weight allocated by suspension

leaf spring which is the major item for weight reduction in

any automobile because steel is used as the major

manufacturing element. The Riding qualities of automobile

can be improved by achieving weight reduction. The weight

of the leaf spring can be reduced without any reduction on

load carrying capacity and stiffness by the introduction of

composite materials like fiber reinforced plastics (FRP).

Because, the fiber reinforced plastics have more elastic strain

energy storage capacity and high strength-to-weight ratio as

compared to those of steel used, mono leaf FRP springs are

replaced with multi-leaf steel springs without any change in

load carrying capacity.

2. Literature Survey

Mahmood M.Shokrieh and Davood Rezaei [1] have studied

the existing model of steel multi leaf spring dimensions and

different loads acting on a spring. Suggest the composite

materials like Glass fibre reinforced plastics for leaf spring

manufacturing. Calculate the stain energies for the both steel

and composite materials. And also given the different joints

to attach the composite leaf springs to the vehicle body.

M.M. Patunkar and D.R. Dolas [2], M. Venkatesan and D.

Helmen Devaraj [3] has made modelling and analysis of

composite leaf spring under the static load condition. They

take the E-Glass/Epoxy material as composite material and

modeling has to be done for both steel and mono E-

Glass/Epoxy materials and also these can be analyzed for

varies loads in ANSYS V10. They concluded that reduction

in weight by 84% for same level of performance using

composite material in static load condition only.

Paper ID: SUB155857 2135





Dadasaheb Gaikwad and Sameer Wagh [4] has given the

brief information about different composite materials used

like fibers and their compositions and also resins with their

compositions. Manufacturing processes suitable for

composite leaf springs.

Sorathiya Mehul and Dhaval B. Shah [5] studied the Analysis

of Composite leaf spring using FEA The determination of the

point of failure during an accident sequence of a rear leaf

spring in a sport utility vehicle is presented in terms of

fracture surface analysis and residual-strength estimates.

Thimmegowda RANGASWAMY, Sabapathy

VIJAYARANGAN [6] has done experiment on the design

optimization of composite drive shafts for power

transmission applications. The one-piece composite drive

shaft is designed to replace conventional steel drive shaft of

an automobile using E-glass / epoxy and high modulus (HM)

carbon/epoxy composites. A formulation and solution

technique using genetic algorithms (GAs) for design

optimization of composite drive shafts has been done. The

purpose of using GA is to minimize the weight of shaft that is

subjected to the constraints such as torque transmission,

torsional buckling capacities and fundamental lateral natural

frequency. The weight savings of the E-glass / epoxy and

high modulus carbon/epoxy shaft were 48.36 % and 86.90 %

of the steel shaft respectively.

Parkhe Ravindra and Sanjay belkar [7] has done the

performance analysis of carbon fibre wih Epoxy resin based

composite leaf spring. They take the carbon/Epoxy leaf

spring properties and also EN47 Steel leaf spring properties.

Manually calculate the bending stresses and also compare

those results in ANSYS software and finally concluded that

Epoxy resin based composite leaf spring have more tensile

strength compared with carbon/Epoxy material.

Anandkumar A. Satpute and S.S. Chavan [8] has briefly

given the manufacturing procedure of composite leaf spring

and also experimentally take the results from UTM also

compare the results with steel leaf spring and finally given

the advantages of composite leaf springs over steel leaf

springs. They choose hand lay-up technique which is an open

type moulding process.

3. Modeling of Leaf Spring Model using

CATIA Software

3.1 Modeling of Steel Leaf spring

In the present work, multi-leaf steel spring and mono-

composite leaf spring are modeled. For modeling the steel

spring, the dimensions of a conventional leaf spring of a light

weight commercial vehicle are chosen. Since the leaf spring

is symmetrical about the neutral axis only half of the leaf

spring is modeled by considering it as a cantilever beam.

Load is applied at the base of the leaf spring in the middle in

the upward direction.

3.2 Specifications for Steel Leaf Spring

MODEL: CDR 650MD 2WD

SUSPENSION: REAR LEAF

SPAN LENGTH: 1120 mm

WIDTH: 50 mm

THICKNESS: 6 mm

OUTER EYE DIA.: 50 mm

DIA.OF CENTRE BOLT: 8 mm

CAMBER: 180 mm

TOTAL NO. OF LEAVES: 10

NO. OF FULL LENGTH LEAVES: 2

NO. OF GRADUATED LEAVES: 8

VEHICLE WEIGHT: 1910 Kg

3.3 Geometric Properties of leaf spring

Camber = 180 mm

Span = 1120 mm

Thickness = 6 mm

Width = 50 mm

Number of full length leaves nF = 2

Number of graduated leaves nG = 8

Total Number of leaves n = 10

Table 1: Design Parameters of Steel leaf spring

Leaf

number

Full leaf

Length (mm)

Half leaf

Length

(mm)

Radius of

Curvature

(mm)

Half

rotational

Angle (Deg)

1 1153.33 576.66 961.11 34.37

2 1153.33 576.66 967.11 34.37

3 1047.97 523.98 973.11 30.84

4 942.64 471.32 979.11 27.57

5 837.31 418.65 985.11 24.34

6 731.98 365.99 991.11 21.15

7 626.65 313.32 997.11 18.00

8 521.32 260.66 1003.11 14.88

9 415.99 207.99 1009.11 11.80

10 310.66 155.33 1015.11 8.76

Figure 1: Solid Model of Steel Leaf Spring






3.4 Specifications for Mono Composite Leaf Spring

Table 2: Geometric Properties of Mono Composite Leaf

Spring Material Half

Length

(mm)

Width

(mm)

Thickness

(mm)

Radius of

curvature

(mm)

Half rotational

Angle (Deg)

Carbon/epoxy 576.66 50 15.25 961.11 34.37

Graphite/epoxy 576.66 50 12.88 961.11 34.37

E-Glass/epoxy 576.66 50 24.45 961.11 34.37

Figure 2: Solid Model of E-Glass/Epoxy Mono Composite

Leaf Spring

Figure 3: Solid Model of Graphite/Epoxy Mono Composite

Leaf Spring

Figure 4: Solid Model of Carbon/Epoxy Composite Leaf

Spring

4. Analysis of Leaf Spring

In the present work, for both multi-leaf steel spring and

mono-composite leaf spring models the Static as well as

modal analysis are carried out by using ANSYS V15 for the

same loading conditions and boundary conditions.

4.1 Static Analysis of Leaf Spring

After prepared the model of the leaf spring by specifications

it has to be subjected to analysis in ANSYS Workbench.

4.1.1Static Analysis of Multi leaf Steel Spring

Static Analysis involves apply meshing, giving boundary

conditions and loads and obtain stress and strain values from

the results obtained by the software.

Material Properties:

Material selected is Manganese Silicon Steel (Steel

55Si2Mn90)

Young’s Modulus E = 2.1E5 N/mm2

Density = 7.86E-6 kg/mm3

Poisson’s ratio = 0.3

Tensile stress = 1962 N/mm2

Yield stress = 1470 N/mm2

Figure 5: Steel Leaf Spring with Boundary Conditions

Figure 6: Deformed and Undeformed Plot of Steel Leaf

Spring

Figure 7: Vonmises-Stress Plot of Steel Leaf Spring

FE analysis for stress and deformation are carried out. The

load of 4000N is applied at the base of leaf spring in the

middle and the eyes of leaf spring are fixed in three

directions i.e. along X, Y and Z axis. We can obtain the

stresses and displacement by performing this analysis. From

the results it is found that the maximum stress is 73.157Mpa

and displacement is 84.834mm which are below the

allowable limits.






4.1.2 Static Analysis of Composite Steel Spring

Three different composite materials have been selected .They

are E-Glass / Epoxy, Graphite / Epoxy and Carbon/ Epoxy

composite materials. Analysis is done by using ANSYS

Workbench.

(a) Static Analysis of E-Glass / Epoxy Leaf Spring

Material properties:

Youngs Modulus = 43E+3 MPa

Poisson’s Ratio = 0.27

Density = 2000kg/m3

Yield strength = 2000MPa

Fig.8 E-Glass/Epoxy Leaf Spring with Boundary Conditions

Figure 9: Total deformation of E-Glass/Epoxy Leaf Spring

Figure 10: Von-Mises Stress Plot of E-Glass/Epoxy Leaf

Spring

(b)Static analysis of Graphite / Epoxy Leaf spring


Young’s Modulus = 294E+3 MPa


Density = 1590kg/m3

Yield Strength = 2067Mpa

Figure 11: Total deformation of Graphite/Epoxy Leaf Spring

Figure 12: Von-Mises Stress Plot of Graphite/Epoxy Leaf

Spring

(c)Static analysis of Carbon / Epoxy Leaf spring


Young’s Modulus = 177E+3 MPa


Density = 1600kg/m3

Yield strength = 1900MPa

Figure 13: Total deformation of Carbon/Epoxy Leaf Spring

Figure 14: Von-Mises Stress Plot of Carbon/Epoxy Leaf

Spring

Under the same loading and boundary conditions i.e. the load

of 4000N applied at the middle of the leaf Spring and the

eyes are fixed in the X,Y and Z directions the results

obtained from the three composite leaf springs for E-

Glass/Epoxy the maximum stress for is 40.66Mpa and

displacement is 34.985mm and for Graphite / Epoxy the

maximum stress for is 146.42Mpa and displacement is

52.959mm and for Carbon / Epoxy the maximum stress for is

100.76Mpa and displacement is 48.03mm which are below

the allowable limits.

4.2 Modal Analysis of Leaf Spring

Modal analysis is carried out to determine the natural

frequencies and mode shapes of the leaf spring. Modal

analysis need only boundary conditions, it is not associated

with the loads applied, because natural frequencies are






resulted from the free vibrations. The boundary conditions

are same as in the case of static analysis.

4.2.1Modal Analysis of Multi leaf Steel Spring

Modal analysis is performed to determine the natural

frequencies and mode shapes of the leaf spring. After the

meshing operation, from solution options, new analysis is

selected as modal in ANSYS Workbench. The subspace

method is selected. In the next step select the no. of modes to

extract and expand are taken as 4.

Figure 15: Total Deformation Plot for 1

st Natural Frequency


nd Natural Frequency

From the modal analysis results, the natural frequencies of

the steel leaf spring are found to be 99.66Hz, 185.48Hz,

338.36Hz and 381.17Hz.

4.2.2Modal Analysis of Composite Steel Spring

Modal analysis is performed to determine the natural

frequencies and mode shapes of the composite leaf spring.

(a) Modal Analysis of E-Glass / Epoxy Leaf Spring






the E-Glass / Epoxy leaf spring are found to be 127.56Hz,

182.88 Hz, 328.05 Hz and 360.46 Hz.

(b) Modal Analysis of Graphite / Epoxy Leaf Spring






the Graphite / Epoxy leaf spring are found to be 291.96Hz,

367.22 Hz, 542.25 Hz and 986.65 Hz.

(c) Modal Analysis of Carbon / Epoxy Leaf Spring











the Carbon / Epoxy leaf spring are found to be 278.41Hz,

290.55 Hz, 514.11 Hz and 820.95 Hz.

5. Calculations

Calculation of load applied on the leaf spring

Vehicle weight = 1910 kg = 1910 x 9.81 = 18737.1N

Load on each leaf spring = 18737.1 / 4 = 4684.275N

Load acting at the eye end = 4684.275 / 2=2342 N

Factor of safety = 1.5

Load applied = 4000 N

Calculation of thickness of mono composite leaf springs

using the formula

Δ = (4 FL 3) / Enbt3

Where

Δ = Deflection of steel leaf spring = 92.591mm (Obtained

from FEA result)

F = Applied load = 4000N

L = Half length of the leaf spring = 566.66mm

n = Number of leaves = 1

b = width of the leaf spring = 50

E = Youngs Modulus = 43 x 103 MPa (E-Glass / Epoxy)

= 294 x 103 MPa (Graphite / Epoxy)

= 177 x 103 MPa (Carbon / Epoxy)

Thickness of E-Glass / epoxy leaf spring = 24.45 mm

Thickness of Graphite / epoxy leaf spring = 12.88 mm

Thickness of Carbon / epoxy leaf spring = 15.25 mm

Calculation of bending stress in the leaf springs using the

formula [9]

σ = 6FL / n bt2

n = 10 (For steel leaf spring)

= 1 (For mono composite leaf spring)

σ = 63.36MPa (Steel leaf spring)

= 48MPa (E-Glass/ Epoxy leaf spring)

= 123 MPa (Carbon / Epoxy leaf spring) = 164MPa (Graphite/Epoxy leaf spring)

6. Results and Discussions

Table 3: Displacement and Stiffness Results Material Displacement (mm) Stiffness (N/mm)

Steel 85 47

E Glass/Epoxy 35 114

Carbon /Epoxy 48 83

Graphite /Epoxy 53 75

Table 4: Theoretical and Ansys Results Material Theoretical Stress

(MPa)

Von-Mises

Stress(MPa)

Steel 75 73

E Glass/Epoxy 48 40

Carbon/Epoxy 123 100

Graphite/Epoxy 164 146

Table 5: Modal Analysis Results Set E Glass/Epoxy

(Hz)

Carbon/

Epoxy(Hz)

Graphite/

Epoxy (Hz)

1 127.56 278.41 291.96

2 182.88 290.55 367.22

3 328.05 514.11 542.25

4 360.46 820.55 986.65

From the table 4, it is observed that the stress in E-Glass /

Epoxy is less than the stress in steel as well as other

composite leaf springs. So from both the stiffness point of

view and based on stress, E-Glass / epoxy can be used for

replacing the steel leaf spring with mono-composite leaf

spring. Since the composite leaf spring is able to withstand

the static load, it is concluded that there is no objection from

strength point of view also, in the process of replacing the

conventional leaf spring by composite leaf spring.

References

[1] Mahmood M.Shokrieh and Davood Rezaei “Analysis and

optimization of a Composite leaf Spring,” ELSEVIER

Journal on Composite Structures 60 (2003) 317 -325

[2] M.M. Patunkar and D.R. Dolas, Modelling and Analysis

of Composite Leaf Spring under the static load condition

by using FEA, International journal of Mechanical &

Industrial Engineering, Volume I Issue 1-2011.

[3] M. Venkatesan and D. Helmen Devaraj, “Design and

Analysis of Composite Leaf Spring in Light Vehicle”

IJMER Vol.2, issue. 1, Jan-Feb 2012 pp-213-218.

[4] Dadasaheb Gaikwad and Sameer Wagh, “Composite leaf

Spring for Light Weight Vehicle – Materials,

manufacturing, process, Advantages & Limitations” in

IJEST Vol 3(2) 2012, 410-413.

[5] Sorathiya Mehul and Dhaval B. Shah, “Analysis of

Composite leaf Spring Using FEA for light Vehicle,” in

JIKRME Vol.02, Issue – 02, Nov 12 to Oct 13.

[6] Thimmegowda RANGASWAMY, Sabapathy

VIJAYARANGAN, " Static And Fatigue Analysis Of

Multi Leaf Spring Used In the suspension System Of

LCV," in IJERA, Vol.02, issue 4, July – August 2012.

[7] Parkhe Ravindra and Sanjay belkar, “performance

Analysis of Carbon Fiber with Epoxy Resin Based

Composite leaf Spring,” in IJCET Vol. 4, No.2, April

2014.

[8] Anandkumar A. Satpute and S.S. Chavan, “Momo

Composite Leaf Spring – Design and Testing,” in

International journal of Applied Research Vol.3, issue 7,

July 2013.

Author Profile






Adapa. Mahanth Kumar is Pursuing M.Tech degree

in Mechanical Engineering from JNTUA College of

Engineering Pulivendula, Kadapa, Andhra Pradesh,

India and Completed B.tech degree in Mechanical

Engineering from Yogi Vemana University, Proddatur

during 2009-2013.

B. Sreenivasa Kumar Reddy is having 8 years

teaching experience and pursuing PhD degree in

“Alternative refrigerants instead of Refrigerants –

R134A if Nano Fluids” from JNTU Anathapur and

completed M.Tech degree in Mechanical Engineering from JNTU

Anathapur and Completed B.Tech in Mechanical Engineering from

JNTU Anathapur.


Documents

Modeling and Analysis of Mono Composite Leaf Spring under ... · The leaf spring have more advantage over helical spring since the ends of the spring may be guided along a definite